First off, I do agree that anyone under the age of 21 who blows below a .08 while operating a motor vehicle should receive an MIP instead of a DUI.  Furthermore, I do feel that the legal drinking age of 21 in the US is a bit absurd.
How many friends have you guys had killed by drunk drivers?  I've had many, and I'm not just talking acquaintances or friends I didn't see outside of school; I mean people whom I was close with, and so many of them that it takes more than the ten fingers on my hands to count them.  I've been drunk illegally as a minor, and I've been legally drunk as an adult.  There have been numerous times when I've been drunk somewhere and needed to be another place, yet I have never in my life driven drunk nor felt the desire.
A little over a year ago, there was a girl in British Columbia (under the age of 19) who used a fake ID to get into a bar.  After getting drunk, she left and STOLE her friend's car.  While she was driving, she hit another vehicle and ended up killing a man in this mid- to late-twenties.  As a punishment, she received 240 hours of community service and nothing more.  When they showed her on the news after the verdict, she was laughing with her friends and obviously felt no remorse.  What kind of a message does this ruling convey?  I knew none of the parties involved in the incident, but I was enraged when I heard the outcome and saw her laughing about the ordeal on the news.
Seriously, though, CALL A FUCKING CAB.  There are many cab companies and/or bars in the US and Canada that will cover your cab fare if you are too intoxicated to drive and need a ride home.
I personally feel that the penalties for receiving a DUI should be harsher, and I definitely support it being a felony.  I also feel that it's bull shit how lenient the courts can be at times for things like killing or injuring another person or persons while driving drunk.  Call me a stupid fucking cunt, or whatever it was, but when you lose nearly twenty loved ones to a MVA caused by an inebriated driver, you might start agreeing with me.  MADD isn't there to fuck you over or ruin your fun; many of the mothers have lost loved ones to drunk driving incidents and are just trying to prevent as many of these instances from happening.
As already stated, I do agree that getting nailed with a DUI (felony = no entry into Canada) for having a BAC of .03 just because you're 18-20 is ridiculous.